Effects of calcium on emergence and seedling growth of castor bean under salinity stress

A growth chamber study was conducted to assess the interactive effects of salinity and Ca 2+ amendment on the emergence and early seedling growth of castor bean (Ricinus communis L.). Seedlings were cultured in wet sands filled with one-half Hoagland solution containing salts either at 0, 50 or 100 mM NaCl. Supplemental Ca 2+ was added at molar mass ratio of NaCl and CaCl 2 of 20 : 0, 20 : 1, 20 : 2 and 20 : 3. Increasing salinity level reduced emergence rate, height and leaf area by up to 34.0%, 26.1% and 46.0% respectively. Calcium amendment increased emergence, height, leaf area, dry plant weight, chlorophyll a, b, chlorophyll (a + b) and soluble protein by up to 22.1%, 13.7%, 21.3%, 30.3%, 28.6%, 24.0%, 25.8% and 42.4% respectively. The present study indicates that the negative effects of salinity on emergence and early seedling growth of castor bean could be lessened with exogenous application of Ca 2+ at appropriate concentrations.